title: Loss of Sh3gl2/endophilin A1 is a common event in urothelial carcinoma that promotes malignant behavior.
abstract: Urothelial carcinoma (UC) causes substantial morbidity and mortality worldwide. However, the molecular mechanisms underlying urothelial cancer development and tumor progression are still largely unknown. Using informatics analysis, we identified Sh3gl2 (endophilin A1) as a bladder urothelium-enriched transcript. The gene encoding Sh3gl2 is located on chromosome 9p, a region frequently altered in UC. Sh3gl2 is known to regulate endocytosis of receptor tyrosine kinases implicated in oncogenesis, such as the epidermal growth factor receptor (EGFR) and c-Met. However, its role in UC pathogenesis is unknown. Informatics analysis of expression profiles as well as immunohistochemical staining of tissue microarrays revealed Sh3gl2 expression to be decreased in UC specimens compared to nontumor tissues. Loss of Sh3gl2 was associated with increasing tumor grade and with muscle invasion, which is a reliable predictor of metastatic disease and cancer-derived mortality. Sh3gl2 expression was undetectable in 19 of 20 human UC cell lines but preserved in the low-grade cell line RT4. Stable silencing of Sh3gl2 in RT4 cells by RNA interference 1) enhanced proliferation and colony formation in vitro, 2) inhibited EGF-induced EGFR internalization and increased EGFR activation, 3) stimulated phosphorylation of Src family kinases and STAT3, and 4) promoted growth of RT4 xenografts in subrenal capsule tissue recombination experiments. Conversely, forced re-expression of Sh3gl2 in T24 cells and silenced RT4 clones attenuated oncogenic behaviors, including growth and migration. Together, these findings identify loss of Sh3gl2 as a frequent event in UC development that promotes disease progression.
authors.affiliation: Urological Diseases Research Center, Boston Children's Hospital 300 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Shyama
authors.initials: S
authors.lastname: Majumdar
authors.forename: Edward M
authors.initials: EM
authors.lastname: Gong
authors.forename: Dolores
authors.initials: D
authors.lastname: Di Vizio
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dreyfuss
authors.forename: David J
authors.initials: DJ
authors.lastname: Degraff
authors.forename: Martin H
authors.initials: MH
authors.lastname: Hager
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Park
authors.forename: Joaquim
authors.initials: J
authors.lastname: Bellmunt
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Matusik
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Rosenberg
authors.forename: Rosalyn M
authors.initials: RM
authors.lastname: Adam
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism; D018450:Disease Progression; D066246:ErbB Receptors / Q000378:metabolism; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D047368:Tumor Burden / Q000235:genetics; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C107640:SH3GL2 protein, human; D050796:STAT3 Transcription Factor; D066246:ErbB Receptors; D019061:src-Family Kinases